Secondary alkyltoluene production



June 115 1957 D. A. MccAuLAY Erm.

SECONDARY ALKYLTOLUENE PRODUCTION Filed NOV. 27, 1955 2,795,632 SECONDARY ALKYLTOLUENE PRODUCTION David A. McCaulay, Chicago, Ill., and Arthur, P. Lien, Highland, Ind., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application November 27, 1953, SerialsNo. 394,711;

Claims. (Cl. 260-671) This invention relates to thev production ofV certain secondary alkyltoluenes. More particularly the invention relates to the production of i'sopropyltoluene and secondary butyltoluene. Still more particularly the invention relates to the production of essentially pure meta isopropyltoluene (m-cymene) and 1,3,5-di-isopropyltoluene (3,5-di-isopropyl-l-methylbenzene) by the interaction of isopropylbenzene and toluene.

The development of the hydroperoxide synthesis for phenol using isopropylbenzene` as the starting material or substituted secondary alkylbenzenesA has resulted in a demand for substituted secondary alkylbenzenes. Since certain phenols have particularly desirable properties for use 'as chemical intermediates, a demand has arisen for large quantities of various substituted secondary alkylbenzenes of highV purity, i. e., about 95%, and also essentially pure, i. e., 99%, compounds. Of particular interest are meta isopropyltoluene and' 1,3,S-di-isopropyltoluene. Meta isopropyltoluene is also of interest to the high poly..- mer industry as a raw material for the manufacture of styrene type plastics having a softening point higher than that of polystyrene.

It is an object of this invention to produce secondary alkyltoluenes. Another object is the preparation ofthe symmetrical 1,3,5-di-sec-alkyltoluene and/ or meta-secalkyltoluene. A particular object is the preparation of l,3,S-di-isopropyltoluene and meta isopropyltoluene. Still another object is a process for the preparation of essentially pure l,3,5-di-sec-alkyltoluene and/or metasec-alkyltoluene by the interaction of a sec-alkyl benzene with toluene.,

High purity 1,3,5-di-secondary alkyltoluene, i..e.,.3,5 di-sec-alkyl-l-m'ethylbenzene, and/or meta, secondary alkyltoluene is prepared by interacting.tolueneanda.sec-

ondary alkylbenzene selectedfrom the class consisting of isopropylbenzene and sec-butylbenzene, either the. mono, the di, or the tri-derivative; a-mol ratio of toluene 4toalkyl groups in the alkylbenzene of at least 0.5 is used. The interaction is carried out in the presenceof atleast enough liquid HF to form a separate acid phase and at kleast.0.5

Ymol of BFa per mol of alkyl groups insaid alkylbenzene.

Themixture of feed and HF-BFa agent is maintained ata temperature of not more than about +40" C. for. atime suliic'ient for the formation of a reaction productcontaining at least `a secondary alkyltoluene fraction which consists of high purity meta sec-alkyltoluene. A product hydrocarbon mixture is obtained by removing the HF and the BFs and high purity l,3,5-di-sec-alkyltoluene and/or rnetal sec-alkyltoluene, lare recovered from the product mixture.

As used herein, interactioninvolves .two alkylbenzenes containing different alkyl groups reacting totransfer an alkyl group from one alkylbenzene tothe other alkylbenzene to form an alkylbenzenecontaining at leasttwo different alkyl groups. Disproportionation as generally understood ditfersfrom interaction in that the two alkylbenzenes involved inthe reaction contain the same alkyl..

' aired States Potent O Fi'ice 2: groups; thus disproportionation involves the reaction of tiwo alkylbenzenes containing the same alkyl groups wherein an alkyl group is transferred from one alkylbenzene to the other alkylbenzene to produce an alkylbenzene containing more alkyl groups .than are present 1n the parent alkylbenzenes.

To illustrate: The process of this invention linvolves the interaction of toluene and an isopropylbenzene to form diisopropyltoluene and/or isopropyltoluene and benzene. In the absence of toluene, isopropylbenzene or sec-butylbenzene undergo a disproportionation to produce the corresponding di-sec-alkylbenzene, tri-sec-alkylbenzene and' benzene.

The secondary alkylbenzene component of the feed to the process `is a member selectedL from the class consisting of secondary alkylbenzene, di-secondary alkylbenzene, tri-secondary alkylbenzene and mixtures thereof, wherein the alkyl groups are selected from the class consisting of isopropyl and' secondary butyl. It is preferred toruse the sec-alkylbenzene and di-sec-alkylbenzenes; to obtain a single product, either an isopropylbenzene or a sec-butylbenzene is charged'.

The other reactive component of the feedl is toluene.

In addition to the toluene andl sec-alkylbenzene, the feed' may contain hydrocarbons which are inert to the action ofthe HF-BF agent and also do not participate t'o any appreciable extent in interaction-withl either toluene or the delinedsec-alkylbenzene. Examples ofV undesirable. aromatic hydrocarbons are xylene, ethylbenzene and t-butylbenzene.

Benzene'- is av by-product ofthe interaction process of this invention. The presence of added benzene in the feed has no significant adverse effect onthe direction of the interaction; however, the presence of large amounts of added benzene in the feed slows down the rate of interaction.

Paraains, particularly theA lower boiling parains, do not in themselves interfere with the interaction. Owing to' theirj low solubility in the acid phase, the presence of morethan a small amount of paraiins, e. g., 3%, in the feed results in the presence of a second' hydrocarbon phase in the reaction zone.

rIlhe presence of a secondfhydrocarbon phase tin the reaction zone, either paratiin or toluene, does have an adverseeffectf on the rateofv interaction. It is preferred to operate under conditions-of feed compositioniand amounts off liquid HF and'BFa usage such that essentially a single homogeneous liquid phase exists in the reaction zone, i. e., essentially all the feed is dissolved in the acid phase.

The feed' tothe interaction process should contain toluene and sec-alkylbenzene in a mol ratio of toluene to sec-alkyl groups, that is determined by the interaction product" distribution. Herein interaction product is intendedto include only sec-alkyltoluene and di-sec-a'lkyltoluene, even though benzene is also produced. The presence of sec-alkyl groups in an amount in excess of the ability of the toluene'present to accept them in the form of di-sec-alkyltoluene and/or sec-alkyltoluene results in the production of disproportionation productsV of the' sec-alkylA benzene and other side reactions. While poly-sec-arlkylbenzenes canbe recycled to the interaction process, it is wasteful; the use of an excess of sec-alkyl groups should be avoidedl The ratiov of toluene to sec-alkyl groups' isfdetermined by the 'interaction product distribution. When the product is exclusively sec-alkyltoluene', at least one mol of toluene is present per mol of sec-alkyl groups charged. When' the interaction product isy exclusively di-sec-alkyltoluene, the mol ratioof toluene to sec-alkyl groups is at least-.0.5; (Under the conditions set'out herein, the interaction product mixture always contain'ssome sec-alkyltoluene'fl When the interaction product is exclusively sec-alkyltoluene, the ratio of toluene to isopropylbenzene or secbutylbenzene charged is at least 1, preferably between 1 and 1.2; and the ratio of toluene to di-isopropylbenzene or di-sec-butylbenzene is at least 2, preferably between 2 and 2.4. When the interaction product is sec-alkyltoluene and di-sec-alkyltoluene-the predominant interaction product, the ratio of toluene to isopropylbenzene or secbutylbenzene is at least about 1, preferably between 1 and 1.2; and the ratio of toluene to di-isopropylbenzeue or cli-sec-butylbenzene is at least about 2, preferably between 2 and 2.4.

The process is carried out under substantially anhydrous conditions. The liquid hydrogen fluoride used should contain not more than about 2 or 3% of water. Commercial grade anhydrous hydrofuoric 4acid is suitable.

Enough liquid HF must be present in the reaction zone to form a separate distinct acid phase. More than this amount is desirable; usually between about 3 and about 50 mols of liquid HF are used per mol of total alkylbenzene feed, i. e., toluene and sec-alkylbenzene charged. The preferred usage of liquid HF is between about 5 and mols per mol of total alkylbenzene feed.

Boro trifluoride, i. e., BF3, must be present in the reaction zone iu at least a catalytically effective amount, for example, 0.1 mol per mol of sec-alkyl groups charged. More than this amount of BFa has a favorable influence on the interaction; at least 0.5 mol per mole of sec-alkyl groups charged should be used, preferably at least about l mol. When the interaction product is exclusively sec-alkyltoluene, at least l mol of BFs should be used per mol of sec-alkyl groups charged. For example, when isopropylbenzene is charged, the BFs usage is at least 1 mol per mol of isopropylbenzene; when di-isopropylbenzeue is charged, the BFS usa-ge is at least 2 mols per mol of di-isopropylbenzene. A large excess of BFa is not necessary.

The interaction is carried out at a temperature of not more than about +40 C. Operation at this temperature for times in excess of about 2 or 3 hours or for shorter times at higher temperatures results in a considerable amount of side reaction products, such as` gas and condensed ring compounds. The interaction may be carried out at temperatures as low as about 40 C., if long contacting times can be tolerated.

The contacting times are dependent on the temperature, product distribution and type of sec-alkylbenzene charged. It is possible to operate under conditions of time and temperature such that, within experimental error, the interaction product is entirely isopropyltoluene or sec-butylto1uene. Under other conditions, the reaction product mixture contains both sec-alkyltoluene and di-sec-alkyltoluene. A mixture can be obtained which contains di-sec-alkyltoluene as the predominant interaction product; however, some sec-alkyltoluene is always present in the reaction product mixture at the conditions set out herein.

When isopropyltoluene or sec-butyltoluene is desired as essentially the only interaction product mixture, the preferred temperature usage is between about -'30 C. and about 0 C. The time of contacting is between about 5 minutes and 2 hours, when mono-sec-alkylbenzene is charged; and between about 15 minutes and 4 hours when di-sec-alkylbenzene is chargedthe longer times corresponding to the lower temperatures. Y

When di-isopropyltoluene or di-sec-butyltoluene is the predominant interaction product, the preferred temperature usage is between about +10 C. and about +30 C. The time of contacting is between about 5 minutes and 1 hour, when mono-sec-alkylbenzene is charged; and

vbetween about 5 minutes and 3 hours when di-sec-alkyibenzene is charged-the longer times corresponding to the lower temperatures. p

When a tri-sec-alkylbeuzene is charged, much longer times are needed than when di-sec-alkylbenzene is charged.

At the preferred conditions of operation the sec-alkyltoluene fraction consists essentially of the meta-isomer and the di-scc-alkyltoluene fraction consists essentially of the 1,3,5-isomer. Operation at higher temperatures for prolonged times results in the production of some of the ortho and para isomers. However, in general the secalkyltoluene fraction contains at least about of the meta-isomer, i. e., consists of high purity meta-isopropyltoluene or meta-sec-butyltoluene.

Even when two distinctliquid phases are present in the reaction zone, the sec-alkyltoluene product is found almost entirely in the acid phase. The sec-alkyltoluene is present in the acid phase in the form of a complex containing l mol of BF3 and probably 1 mol of HF per mol of sec-alkyltoluene. When operating with the preferred amounts of toluene, the excess toluene is physically dissolved in the acid phase.

PRODUCT RECOVERY The reaction product mixture may be recovered from the acid phase by various methods. Probably the simplest procedure and one most suitable for laboratory work consists of adding the acid phase to crushed ice; and the acid phase may be contacted with aqueous alkaline solution, such as sodium hydroxide, potassium hydroxide and ammonia. It is desirable to prevent rearrangement reactions by the use of a cold aqueous reagent.

The hydrocarbons originally present in the acid phase appear as an upper oil layer above a lower aqueous layer. The upper oil layer may be separated by decantation and may be treated with dilute aqueous alkaline solution to remove any HF and BFg occluded therein.

Both HF and BF3 are relatively expensive chemicals and it is desirable in an economic process to recover these and to recycle them for reuse in the process. The HF and the BFs may be readily removed from the acid phase by heating the acid phase or by applying a vacuum thereto. The HF and the BFa distill overhead and may be recovered for reuse in the process. When di-alkylbenzenes and/ or tri-alkylbenzenes are the principal complex-forming hydrocarbons, the complex may be decomposed at relatively low temperatures by the use of vacuum distillation or by stripping with a low boiling inert hydrocarbon, such as a parain.

The reaction proceeds from the time that the complex is formed until the complex is decomposed, assuming that a suitable temperature exists. When it is desired to produce essentially only sac-alkyltoluene reaction product, for example, meta isopropyltoluene, it is necessary to take into account the total time elapsing from the time that the complex has been formed till the time that it has been decomposed in the distillative decomposition procedure. Thus, when using distillative decomposition procedure, it is necessary to consider the residence time of the complex in the decomposing zone as a part of the contacting time. Also, it is necessary to consider the temperature maintained in the decomposing zone. Generally the temperature in the decomposing zone should be no higher than the possible maximum usable in the contacting zone.

Di-sec-alkyltoluene at moderate temperatures disproportionates very slowly to the corresponding tri-derivative. Therefore, it is possible to distillatively decompose the complex of (ii-secondary alkyltoluene at temperatures as high as +40 C. Somewhat higher temperatures may be used if the acid phase is very rapidly raised to the decomposition temperature and the HF and BFa are very rapidly removed from the acid phase. f

The recovery of the meta secondary alkyltoluene product without back isomeirzation `to ortho and para isomers or disproportionation to the cli-secondary alkyltoluene is the most diicult recovery to be made by distillative decomposition of the complex. Itis obvious that operation at -very low temperatures such as 0 C. or lower involves au expensive high vacuum operationsinceliquid HF boils .at C. at atmospheric pressure.

Theppreferred method of recovering high purity meta secondary alkyltoluene from an acid phase without back isomerization or disproportionation is the displacement of Athe meta secondary alkyltoluene from its HF andn BFS complex by an alkylbenzene Whichforms amore stable HFandBFa complex. Broadly, the displaceris a polyalkylbenzene containing at least three alkyl groups which alkyl groups are selected from the class consisting of n'ormaland' secondary and which contain not more than four carbon atoms. Normal alkyl groups are methyl, ethyl, n-propyl fand. nfbutyl.- The secondary alkyl groups are isopropyl and secondary butyl.l

Pentamethylbenzeue and hexamethylbenzene are particularly effective displacers. However, the complexes formed by these compounds are `so stable that quite elevated temperatures a-re necessary to` decompose the complex'es in Vorder-to recover ftheHF and'BFa.

The preferred tri-allylbenzenes have4 the symmetrical configuration, i. e., 1,3,5-tri-a1kylbenzen`e. The preferred tet-ra-falkylbenzenes possess the 1',2,3,5 configuration. These displacers are preferred because they do not tend to undergo rearrangement reactions and have better displacement etfectiveness than the other isomers. The preferred displacers are mesitylene, tri-isopropylbenzene, di-isopropyltoluene and isodurene.

As it is normally impractical to operate under conditions wherein absolutely no iii-secondary'alkyltolueneis produced, it is desirable to operate with'a displacerl which will.n`ot` complicate the problem of recovering the byproduct, di-secondary alkyltoluene. Therefore, it is preferred to use -as the displacer in the process of this invention a poly-'secondary alkyltolu'ene, for example, di-isopropyltolueue or di-secondary butyltolnene, corresponding to the sec-alkyl group charged.

Theoretically, l mol of added displacer will replace l. mol of secondary alkyltoluene. However, greater lamounts of displacer should be used. The amount of displacer used is dependent upon the total recovery of secondary alkyltoluene desired and also the effectiveness of the contacting of the acid p'hase and the displacer. It is preferred to operate with between about 2 and 6 mols of .displacer'per mol of secondary alkyltoluene present in the .acid phase.

The `acid phase possesses an extremely high solubility for aromatic hydrocarbons. Quite a large amount of displacer can be added to the acid phasewithout apparently displacing any secondary alkyltoluene. By the use of large amounts of displacer, it is possible to produce a second liquid phase which comprises displaced secondary alkyltoluene and displacer. i

Since parainic hydrocarbons are soluble in the acid phase to only a relatively small extent, it is possibleV to was-h from the acid phase-displacer solution the displaced' secondary alkyltoluene. The wash hydrocarbon mustv be inert tothe action of HF and BFafand ,nonreactive with the; sec-alkyltoluenes present inthe acidphase. Benzene maybe used asia wash hydrocarbon. Itlislpreferred to use las thev inert hydrocarbon a lou/boiling liquid paraffin, such as, propane, buta'ne, pentane and hexane.

Thewashhydrocarbon may be introduced into the acid phase-,displacer solution simultaneouslywith the displacer, preferably as a single solution; or the washhydrocarbon` maybe introduced into the acid phase after the additionA of the-displacer.

In order to avoid rearrangement reacl-f tions, it -is preferred to introduce the wash hydrocarbon- Y substantially simultaneously after the introduction ofthej` displacer. i

Itis-:preferred to carry` out the displacement operation; in acontinuous countercurrent apparatus; in `such anoperation the acid phase is introduced in Aan upper portionfofl the tower, the displacer is introduced at la lower portion of the'towerfan'd the inert wash hydrocarbon is introducedA at a point-below the point of entry of the displacer."4""V i The lamount ,of inert wash hydrocarbonintroduced must be enough to` remove substantially all the displaced secondary alkyltoluene. In genenal, the amount ofinert wash hydrocarbon used is between about 50 andl500 volume percent Vbased on secondary alkyltoluene displaced, preferably, between about 15G-and 250 volume percent.

The displacingzone should beY operatedv at atempenature and. for a' contacting rtime such that essentially no rearrangement-reactions. take place therein. Thus, the contacting timein the displacing zone and the temperature therein must be consideredin determining the total contacting time to be utilized in the process.

ILLUSTRATIVE EMBODIMENT The tannexedtigure, which forms a part of this specification, showsfan illustrative embodiment of a method of carrying out the invention to produce essentially pure meta .isopropyltolueneV by'interacting` isopropylbenzene :and 'toluene'.` `Tlieii'gure.isschematic and many items of equipmenthave been omitted, such as pumps, valves, etc., as these mayfbereadily added thereto.

IS.OplropylbQenzeneV fromsource` 11 is passed by vway of lines 12'ai1dy 13 into heat exchanger 14. From exchanger 14.-it is passedby wayof -line16.intorline17.

Toluene from,source319fispassed by waylof-valved line'21 and line 22l into heat exchanger 23. From exchanger 23, the added toluene land recycled toluene are passed by, way of line 24.into line 17. The toluene to isopropylbenzene ratio is 1.1. l Y

Anhydrous liquid hydrogen uoride, 14 mols/mol of total :alkylbenzene feed, is passed from the line 26, through heatexchanger 27 and line 28,intoline-1f7. Heat exchangers 14, 23 and 27 bring the. temperature of the isopropylbenzene, toluene andthe liquidHF to a temperature of about 20J C. This temperature is about 10 lower than the desired reaction temperature of 10 C.

The contents of line 17 are introduced into mixer 31 which is provide-d with heat exchanger means 32. 1.2 mols of BFS p er mol of isopropylbenzene from line 29 is introduced into mixer 31. Mixer 31 is an apparatus able to rapidly intermingle the hydrocarbons, liquid HF and BFS. The heat exchanger means 32 withdraws heat of complex formation and prevents the temperature at the discharge end of mixer 31 rising above 10 C.

An acid phase consisting of liquid HF, dissolved complex, toluene and BFS is discharged from mixer 31. About p. s. i. g. of pressure `are maintained on the system to keep the excess'BFa in the acid phase. The essentially single homogeneous acid phase is passed from mixer 31 by way of line 33 into reactor 34.

Reactor 34 is provided with heat exchanger means 36 and 37. Agitation is not needed to assist the reaction rate because Vof theA single phase system existing in the reactor. To insure the maintenance of a substantially uniform temperature of 10 C. throughout the reactor, vreactor M is provided with battles 33a, 38b and 38C and motor driven agitator 39.

The acid phase is withdrawn from the top of reactor 34 and is passed by way of line 41. into the upper portion of displacing zone` 42. The contacting time is measured as the time inl mixer 31, reactor 34 and part of the total time in displacing zone 42. In this embodiment, a total time of-about l5- minutes is utilized.

Displacingzone 42 consists of a vertical Vessel adapted for intimate contacting of two immiscible phases in a continuous countercurrent manner. In this embodiment, the displacer, di-isopropyltoluene from source 46 is passed by way Of-lines 47 and 4S into heat exchanger 49. The contents of line, 48, i. e., outside and recycled di-isopropyltolueneare brought to a temperature of 10 C. in heatexchanger 49 and are then introduced by way of line Slvinto v.a lower intermediate portion of displacing zone Y 42.V In thisr embodiment, 4 mols of displacer are introduced molofisopropyltoluene introduced into the displacing zone from line 41.

heat exchanger 57 to 10 C. and introduced by way of line 58 into a lowerportion of displacing zone 42, at a point below the entry of displacer from line 51. In this embodiment, 200 volume percent of pentane, based on isopropyltoluenes introduced from line 41, is introduced into displacing zone 42.

A ratlnate phase is withdrawn overhead from zone 42. This consists essentially of pentane, benzene, toluene, meta 'isopropyltoluene, di-isopropyltoluene Yand some slight amount of HF and BFa. 'Iherainate phase is introduced by way of line 61 into fractionation zone 62. This zone 62 is shown schematically since one skilled in the distillation art can devise the proper method of separating the raffinate phase into a pentane fraction, also including the HF and BFs; a benzene fraction; a toluene fraction; a product meta-isopropyltoluene fraction and a displacer fraction.

A pentane fraction, which includes the HF and BFa present in the rainate phase, is withdrawn and passed by way of lines 66 and 67 to line 56 for reuse in the displacing zone 42.

' AY benzene fraction is withdrawn from zone 62 and passedto storage by way of line 70. A toluene fraction is withdrawn and is recycled for reuse by Way of lines 71 and 72.

A product fraction consisting essentially of meta isopropyltoluene is withdrawn from zone 62 by Way of line 74. A bottoms fraction consisting of 1,3,5-di-isopropyltoluene is withdrawn by way of line 76 and recycled to zone 42 by way of line 79. Only a very slight amount of di-isopropyltoluene is made in this process; in general this production about balances the physical losses. Sme times di-isopropyltoluene may be added or it may be withdrawn from the system. The necessary amounts of diisopropyltoluene are made by operating the unit under conditions conducive to making this product.

The extract (acid) phase is withdrawn from displacing zone 42 and is introduced by way of line 86 into decomposing zone 87. Decomposing zone 87 is provided with internal heater 88 and some fractionation means, not shown. The temperature of +40 C. in zone 87 is high ybut not high enough to disproportionate.

HF vapor and BF3 gas are Withdrawn from zone 87 and passed by Way of line 91 into heat exchanger 92. In heat exchanger 92, the HF vapors are condensed and a liquid-gas stream is passed by way of line 93 into gas separator 94. BFaA is withdrawn from gas separator 94 and is recycled by way of lines 96 and 29 to mixer 31. Make-up BFa is introduced from source 98 by way of valved line 99 into line 96. Liquid HF is recycled by way of lines 101 and 26. Make-up HF is introduced from source 102 by way of valved line 103 into line 101.

The hydrocarbon fraction is withdrawn and introduced by Way of line 106 into fractionation zone 107, shown schematically herein. A pentane fraction is withdrawn and recycled by way of lines109 and 67, etc. to displacing zone 42. A benzene fraction is Withdrawn by Way of line 110. A toluene fraction is withdrawn and recycled by way of lines 111 and 72, etc. to mixer 31. A bottoms fraction consisting of di-isopropyltoluene and a very slight amount of isopropyltoluene, is withdrawn by way of line 113 and recycled -to zone 42 by Way of line 79.

EXAMPLES The results obtainable by the invention` are illustrated by the following examples: The runs were carried out using a carbonsteel reactor provided with a 1725 R. P. M. stirrer. The agent and reactants were added in the following order: (l) the alkyl group donor, (2) the alkyl group acceptor toluene, (3) commercial grade anhydrous HF and (4) commercial grade BFa.

The contents of the reactor were agitated during the addition of the HF and BFa. The contacting was continued at about constant temperature for the desired time.

The contents of the reactor were withdrawn into a vessel iilled with crushed ice. An upper hydrocarbon layer formed over an aqueous layer. The hydrocarbon layer was decanted and washed with dilute ammonium hydroxide solution to remove HF and BFa. The hydrocarbons Were -then water washed to remove ammonium hydroxide.

The hydrocarbon mixture was fractionated in a distillation column providing about 30 theoretical plates. Each product fraction was analyzed by a combination of boiling point, specific gravity, refractive index, ultraviolet and infrared spectra.

Table I Run No 1 2 3 4 Charge: Di- Isopro yl- -di-t-bu l- Donor, type Ethylbenzene ethylbeuzene benzeiie p benzen7 mols percent mols percent mols percent mola percent Donor 1. 44 46 0. 81 33 1. 43 50 0. 82 27 Toluene 1. 54 L 65 67 1. 44 50 2. 17 73 1. 15 1. 02 1. 01 1. 32 35 30 37. 5 30 4. 4 2. 36 3. 09 3. 43 11. 3 12. 2 13. 1 10. 0 3. 06 1.46 2. 16 2. 09 is at as sa 30 30 30 15 96 90 37. 2 6. 3 42.7 26. 1 25. 7 45. 0 14. 0 32. 1 0. 8 0.0 0. 5 0. 0 25. 2 19. 1 34. 5 28. 7 8. 5 29. 6 2. 5 0. 0 1,3, 5-d1alkyltoluene 1. 0. 0 5. D 16. 2 Higher boiling 0. 0 0. 0 0. 0 l. 9

The fdetailed results of thedinteraction of tolueneand di;t-butylbenzene,` isopropylbenzene and ethylbe v es, respectively, are slown'inA Table I. Runs with dvi-t-bultylbenzene Vand,l ethylbenzenes are'shown Vfor comparison.

In `rtlnflvQS %`ofY the "ethylbenzene. charged was converted. v About one-third of the' yethylbenzene 'disproportionated to m-di-ethylbenzene. Less than 10% of the interacted ethyl groups passed to 1,3,5-di-ethyltoluene. No tri-ethyltoluene or tri-ethylbenzene were produced. (In all runs the di-alkylbenzenes were meta isomer and the tri-alkylbenzenes were the 1,3,5-isomer, that is, within the error of infrared determination.)

Run 2 shows that di-ethylbenzene does not give the same product distribution as ethylbenzene, when operating at substantially the same conditions. Only 23% of the di-ethylbenzene interacted. Most surprisingly none of the di-ethylbenzene disproportionated to tri-ethylbenzene; also no ethylbenzene was produced. Runs 1 and 2 show that di-ethylbenzene is not as reactive as ethylbenzene and that with di-ethylbenzene charge the interaction is readily halted at the exclusively meta-ethyltoluene product stage.

In run 3 about 99% of the isopropylbenzene charged was converted. Only 5% of the isopropylbenzene disproportionated to produce di-isopropylbenzene-no triisopropylbenzene was formed. About 30% of the interacted isopropyl groups went to form di-isopropyltoluene. This compares with only in the case of ethylbenzene in run 1. (The disparity is actually greater since run 3 was at a lower temperature than run 1.)

The extreme mobility of t-butyl groups is well shown in run 4. Even though the feed was a di-t-butylbenzene and the conversion was carried out at a lower temperature and for only one-half the time of the other runs, all of the di-t-butylbenzene interacted. In the absence of toluene, di-t-butylbenzene disproportionates to a mixture of mono-diand tri-t-butylbenzene. Despite the low temperature and time an appreciable amount of side-reactions took place to produce high boiling material. Here about 60% of the interacted t-butyl groups went to form di-t-butyltoluene.

Quite a startling difference exists between the product distribution of run 2 (di-ethylbenzene) and run 4. Runs 1, 3 and 4 show that di-t-butylbenzene is much more reactive than isopropylbenzene and very much more reactive than ethylbenzene. These runs show that the interaction characteristics of the ethyl, isopropyl and tbutyl groups are not predictableone from the other.

Thus having described the invention, what is claimed 1. An interaction process which comprises contacting, under substantially anhydrous conditions, a feed comprising essentially (a) toluene and (b) a member selected from the class consisting of sec-alkylbenzene, di-sec-alkylbenzene, tri-sec-alkylbenzene and mixtures thereof, wherein the alkyl groups are selected from only one member of the class consisting of isopropyl and sec-butyl, as essentially the only reactive components, in a mol ratio of toluene to sec-alkyl groups in said sec-alkylbenzene of at least 1, with between about 3 and 50 mols of liquid HF per mol of total alkylbenzene feed and at least 1 mol of BFa per mol of sec-alkyl groups in said secalkylbenzene, at a temperature between about -40 and +40 C. for a time sufficient for the formation of a fraction consisting of high purity meta-sec-alkyltoluene, removing HP and BFS to recover a product hydrocarbon mixture and recovering therefrom a fraction consisting of high purity meta-sec-alkyltoluene.

2. The process of claim 1 wherein said sec-alkylbenzene is isopropylbenzene, the temperature of contacting is between about 30 C. and about 0 C., the time of contacting at 0 C. is about 5 minutes and about 2 10 hours at. .e301 thaloasmimes .cor'tss'psnfling to the lower temperatures', and the'product hydrocarbon mixture contains a'sfe'ssentially the -only interaction product aafrfactionconsisting essentially ofmeta isopropyltoluene.

s; The processor anatra/herein, 'said sec-altrimenzene is iii-isopropylbenzene, said'temperture of contacting is between about -30 C. and about 0 C. at a time of about 5 minutes at 0 C. and about 4 hours at -30 C., the longer times corresponding to the lower temperatures and said product hydrocarbon mixture contains as essentially the only interaction product a fraction consisting essentially of meta isopropyltoluene.

4. The process of claim 1 wherein said sec-alkylbenzene is isopropylbenzene and said contacting temperature is between about y}-10 C. and about +30 C. at a time of about 5 minutes at ,'-l-SO" C. and about one hour at -l-10J C., the longer times corresponding to the lower temperatures and said reaction product mixture containing a fraction consisting essentially of meta isopropyltoluene and a fraction consisting essentially of 1,3,5-diisopropyltoluene, said di-isopropyltoluene being the predominant interaction product.

5. The process of claim 1 wherein said sec-alkylbenzene is di-isopropylbenzene and said contacting temperature is between about +10 C. and about .-|30 C. at a time of about 5 minutes at +30 C. and about 3 hours at -[-l0 C., the longer times corresponding to thelower temperatures, and said reaction product mixture containing a fraction consisting essentially of meta isopropyltoluene and a fraction consisting essentially of 1,3,5-diisopropyltoluene, said di-isopropyltoluene fraction being the predominant interaction product.

6. An interaction process which comprises contacting, under substantially anhydrous conditions, a feed comprising essentially (a) toluene and (b) a member selected from the class consisting of sec-alkylbenzene, di-sec-alkylbenzene, tri-sec-alkylbenzene and mixtures thereof, wherein the alkyl groups are selected from only one member of the class consisting of isopropyl and sec-butyl, as essentially the only reactive components, in a mol ratio of toluene to sec-alkyl groups in said sec-alkylbenzene of at least 1, with between about 3 and 50 mols of liquid HF per mol of total alkylbenzene feed and at least 1 mol of BFa per mol of sec-alkyl groups in said secalkylbenzene, at a temperature between about 40 and +40 C. for a time sufficient for the formation of a fraction consisting of high purity meta sec-alkyltoluene, contacting the acid phase from the interaction step with at least about 1 mol of a displacer per mol of secondary alkyltoluene present in said acid phase and substantially simultaneously thereafter with an amount of an inert liquid hydrocarbon suicient to extract from said acid phase displaced secondary alkyltoluene, at a temperature below about 0 C. for a time such that substantially no rearrangement reaction takes place, and separating a rainate phase comprising inert hydrocarbon and secondary alkyltoluene from an acid phase comprising HF, BFS and displacer and recovering from said rafnate phase a secondary alkyltoluene comprising essentially the meta isomer, and wherein said displacer is a poly-alkylbenzene containing at least 3 alkyl groups that are selected from the class consisting of normal and secondary, which contain not more than 4 carbon atoms.

7. The process of claim 6 wherein said displacer is isodurene.

8. The process of claim 6 wherein said displacer is 1,3,S-di-isopropyltoluene.

9. The process of claim 6 wherein said hydrocarbon is hexane.

10. The process of claim 6 wherein said hydrocarbon is pentane.

(References on following page) 2,420,073 Frey May 6, 1941 5 2,725,413

12 Kemp Oct. 31, 1950 Lien Nov. 7, 1950 Lien Aug. 14, 1951 Corson et al Mar. 11, 1952 McCaulay et al Nov. 29, 1955 www 

1. AN INTERACTION PROCESS WHICH COMPRISES CONTACTING UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS, A FEED COMPRISING ESSENTIALLY (A) TOLUENE AND (B) A MEMBER SELECTED FROM THE CLASS CONSISTING OF SEC-ALKYLBENZENE, DI-SEC-ALKYLBENZENE, TRI-SEC-ALKYLBENZENE AND MIXTURES THEREOF, WHEREING THE ALKYL GROUPS ARE SELECTED FROM ONLY ONE MEMBER OF THE CLASS CONSISTING OF ISOPROPYL AND SEC-BUTYL, AS ESSENTIALLY THE ONLY REACTIVE COMPONENTS, IN A MOL RATIO OF TOLUENE TO SEC-ALKYL GROUPS IN SAID SEC-ALKYLBENZENE OF AT LEAST 1, WITH BETWEEN ABOUT 3 AND 50 MOL OF LIQUID HF PER MOL OF TOTAL ALKYLBENZENE FEED AND AT LEAST 1 MOL OF BF3 MOL OF SEC-ALKYL GROUPS IN SAID SECALKYLBENZENE, AT A TEMPERATURE BETWEEN ABOUT -40* AND +40*C. FOR A TIME SUFFICIENT FOR THE FORMATION OF A 